Repeated single-limb postural stability testing elicits a practice effect

The effects of pressure biofeedback on hip and trunk muscle activity and lumbopelvic alignment during one-leg standing

BACKGROUND: During one-leg standing (OLS), optimum activity of the gluteus medius (Gmed), multifidus (MF), and quadratus lumborum (QL) muscles relies upon maintaining neutral lumbopelvic alignment. However, no studies have examined how using pressure biofeedback during OLS affects the activity of these muscles and the concomitant alignment of the pelvis and trunk. OBJECTIVES: The purpose of this study was to investigate the effect of pressure biofeedback on the activity of the Gmed, MF, and QL and the femoropelvic and trunk lean angles during OLS. METHODS: Twenty-four healthy males performed OLS with (PB+) and without (PB-) pressure biofeedback. For all OLS conditions, a pressure sensor was placed between the lateral surface of the humerus on the non-supporting side and the wall. Under the PB- condition, participants performed preferred OLS while the examiner measured the maximum pressure caused by trunk lean. Under the PB+ condition, participants were asked to perform at a threshold of 50% of the maximal pressure (PB+ 1 condition) and with minimal change in pressure (PB+ 2 condition). Muscle activities of MF, QL, and Gmed as well as the femoropelvic and trunk lean angles were measured under various OLS conditions. RESULTS: The activity of the Gmed, MF, and QL was greater under both PB+ conditions than under the PB- condition (p< 0.05). Also, both PB+ conditions resulted in a greater femoropelvic angle and reduced trunk lean angle. There were no significant differences in muscle activity, femoropelvic angle, or trunk lean angle between PB+ 1 and PB+ 2 (p> 0.05). CONCLUSIONS: These results suggest that pressure biofeedback is a useful modality for increasing the activity of the Gmed and trunk muscles, especially the MF muscle on the non-supporting leg side, and for preventing compensatory movements such as trunk deviation and pelvic lateral deviation during OLS.

Youth Baseball Pitching Stride Length: Normal Values and Correlation With Field Testing

BACKGROUND

Pitching biomechanical analysis has been recommended as an important component of performance, injury prevention, and rehabilitation. Normal values for youth pitching stride length have not been established, leading to application of normative values found among professional pitchers to youth pitchers.

HYPOTHESES

The average youth pitching stride length will be significantly less than that of college and professional pitchers. There will be a positive correlation between stride length, lower extremity power, balance, and pitching experience.

STUDY DESIGN

Prospective cohort study.

LEVEL OF EVIDENCE

Level 3.

METHODS

Ninety-two youth baseball pitchers (aged 9-14 years) met the inclusion/exclusion criteria and completed the study. Stride length was recorded using a Dartfish video system over 3 maximal effort pitches. Both intra- and interrater reliability was calculated for the assessment of stride length. Double-leg vertical jump, single-leg stance time, leg length, weight, age, and pitching experience were also recorded.

RESULTS

Mean (SD) stride length was 66.0% (7.1%) of height. Stride length was correlated ( P < 0.01) with vertical jump (0.38), pitching experience (0.36), and single-leg balance (0.28), with excellent intra- and interrater reliability (0.985 or higher). No significant correlations between stride length and body weight, leg length, or age existed.

CONCLUSIONS

There was a significant difference between youth pitching stride length and the current published norms for older and more elite throwers. There was a positive correlation between stride length and lower extremity power, pitching experience, and single-leg balance.

CLINICAL RELEVANCE

Two-dimensional analysis of stride length allows for the assessment of pitching biomechanics in a practical manner. These values can be used for return to pitching parameters after an injury and designing injury prevention and performance programs.

Effect of foot position on balance ability in single-leg stance with and without visual feedback

The purpose of this study was to determine the natural foot position and to quantify the effect of foot position on balance performance during single-leg stance. Forty healthy subjects participated in this study (age, 18 to 32 years; 24 female). Subjects were asked to perform single-leg balance trials on a balance force plate in their self-selected and four predetermined foot positions with their eyes open and closed. Sway distance, area and velocity were computed for each trial. There was significant interactions between visual conditions and foot position for all sway parameters (P<.001). With the eyes closed, sway parameters were greatest for the self-selected foot position compared to the other foot positions (P<.005). No differences in sway parameters between foot positions were detected for the eyes-open condition. Sway distance, area and velocity were 94%, 400% and 89% greater, respectively, for the eyes-closed than the eyes-open condition. Self-selected foot placement did not produce the most stable single-leg stance. The results of this study indicate that foot position is not important for protocols for assessing balance or for rehabilitation exercises using eyes-open conditions and that assessment protocols and rehabilitation exercises should clearly specify the foot position when using eyes-closed protocols.

Control of posture during tasks representing common work-related postures - a reliability study

Assessment of control of posture using a task battery that represents work-related postural conditions is highly recommended for providing a comprehensive understanding of collective postural demands. However, dearth of evidence exists on the reliability of a task battery, thus precluding its use as an outcome measure in field research. This study investigated the intrasession reliability and systematic variation of force plate derived centre of pressure (COP) measures obtained during repeated performance of a task battery (lifting task, limits of stability and bipedal and unipedal stance). COP signals obtained during each task performance were processed to derive various time-domain COP measures. Statistical analyses revealed that 13 of the 19 COP measures displayed excellent relative (ICC(2,3) ≥ 0.75) and acceptable absolute reliability (SEM%: ≤ 10). Although COP measures displayed systematic variation, the differences were less or equal to the measurement error, except COP measures of unipedal stance and limits of stability. The chosen task battery is reliable and can be used for comprehensive evaluation of control of posture, in both field and laboratory research. Practitioner Summary: Repeated evaluation of multiple tasks together sequentially could introduce measurement variability. This study investigated intrasession reliability of a task battery representing common work-related postures. The chosen task battery was found to be reliable with acceptable measurement error and can be used in field research settings for evaluation of control of posture.

The effect of the Nintendo Wii Fit on balance control and gross motor function of children with spastic hemiplegic cerebral palsy

OBJECTIVE

To study the impact of training using the Nintendo Wii Fit in 14 children with spastic hemiplegic cerebral palsy.

METHODS

A single-subject single blinded design with multiple subjects and baselines was utilised. Interactive video gaming (IVG) in lieu of regular physiotherapy was given for 3 weeks. Outcome measures included modified balance and running speed and agility (RSA) scales of the Bruininks-Oserestky test of Motor Performance 2 and the timed up and down stairs (TUDS).

RESULTS

Balances score improved significantly (F(2, 26) = 9.8286, p = 0.001). Changes over time in the RSA (F(2, 26) = 0.86198, p = 0.434) and the TUDS (F(2, 26) = 1.3862, p = 0.268) were not significant. Ten children preferred the intervention to conventional physiotherapy.

CONCLUSION

Most children preferred the IVG but as the effect did not carry over into function, IVG should not be used in place of conventional therapy and further research is needed into its use as an adjunct to therapy.

Normative values for three clinical measures of motor performance used in the neurological assessment of sports concussion

Postural control and motor coordination are essential components of normal athletic activity. Tasks involving balance and coordination are used to determine neurological function in sports-related concussion. Determining normative values for these tasks is therefore essential to provide sports medicine professionals with a frame of reference with which to interpret clinical measures obtained from players suspected of sustaining a concussion. One hundred and seventytwo healthy subjects (16-37 yrs) performed three timed tests: Tandem Gait (TG); Finger-to-Nose (FTN); Single-Leg-Stance (SLS) on firm and foam surfaces. Unadjusted geometric means (+/-SD) for each measure were averaged across three trials. Time to complete TG was 11.2+/-1.2s. FTN for the dominant and non-dominant arm were 2.9+/-1.1s and 3.0+/-1.2s, respectively. SLS values for dominant and non-dominant leg were 20.4+/-3.0s (firm), 3.4+/-1.6s (foam), and 21.0+/-2.9s (firm), 3.3+/-1.6s (foam), respectively. For TG, there was an order effect (P<.001) but no age, sex or BMI effects. FTN demonstrated a dominant arm preference (P<.001), sex (P=.006), BMI (P=.043) and order effects (P<.001). SLS demonstrated an order effect on the firm surface (P=.009) and an order (P<.001) and BMI (P=.001) effect on foam. Intra-rater reliability, as measured by ICC (3,3), demonstrated that TG and FTN had excellent reliability compared to SLS. FTN and TG should continue to be used in test batteries to determine neurological function in sports-related concussion.